Formatting the "age" cell B1 to date does not give the correct answer, if the date of birth is for instance 1 jan 1012, the date today is set to 1 jan 2013 the substarcted value displayed in date format is 31 days, 12 months and 00 years, which is incorrect.
I found a function in the internet called DATEDIF which interestigly is an "undocumented" function but that does nothing different or new compared to simple substraction of the cells containing DOB and TODAY.. both give the number of days between two dates.

I found an another Integer formula that works, just seems awfully complicated for a simple calculation, I thought Excel would have something simple to solve that common question.